Many industrially manufactured products are produced continuously and with high piece numbers. In the process, it is often necessary to weigh the products, for example, in order to feed a certain quantity of a product, mostly determined by the weight, to an associated packaging unit. The moving product streams here have to be weighed to avoid delays, while they are conveyed, often at high speed, through the production installations. Weighing here has a control function, as it is used in order to make it possible to check the products with regard to weight, their completeness within the packaging unit, etc.
For this purpose, scales are known that have conveyor belts that rest on a weighing cell. The conveyor belt forms a preliminary load for the weighing cell. While the product stream continues to be moved by the conveyor belt, it can be simultaneously weighed. However, the construction of such conveyor belts is expensive, it is difficult to avoid a force shunt particularly on the motor cable, and the cleaning of the components of such a conveyor belt is also expensive.
Weighing chutes are known from the prior art, wherein the product stream glides sidewise over a sliding surface that is inclined with respect to the horizontal. The chute here forms an initial load for a weighing cell for determining the weight of the product stream while it slides over the weighing chute. In order to eliminate the influence of friction effects or other dynamic forces that act along the sliding direction on the weighing chute, the weighing cell is arranged with its load introduction direction as perpendicular as possible to the sliding surface or the transport direction of the weighing chute. In this manner, the dynamic forces resulting from the movement of the product due to acceleration/deceleration always act transversely to the load introduction and therefore they have no effect on the measured result.
In comparison to driven conveyor belts, weighing chutes of simpler design can be manufactured, and they are easier to clean and nearly wear-free, whereas in the case of conveyor belts the wearing at belts and/or shafts cannot be avoided over the long term.
From DE 689 083 64 T2, such a device for weighing a continuous stream of flowing material is known. DE 199 47 394 A1 also describes a method and a device for measuring bulk product streams. However, the two methods and devices disadvantageously require the determination of the speed of the bulk product, because no absolute weight value can be formed without determining the speed. For the determination of the speed of the bulk product, various methods can therefore be considered, which are technically elaborate and associated with errors. The device is not suited for determining the weight of detached or discrete weighing products.